title: Expression, stability, and replacement of glucan-remodeling enzymes during developmental transitions in Saccharomyces cerevisiae.
abstract: Sporulation is a developmental variation of the yeast life cycle whereby four spores are produced within a diploid cell, with proliferation resuming after germination. The GAS family of glycosylphosphatidylinositol-anchored glucan-remodeling enzymes exemplifies functional interplay between paralogous genes during the yeast life cycle. GAS1 and GAS5 are expressed in vegetative cells and repressed during sporulation while GAS2 and GAS4 exhibit a reciprocal pattern. GAS3 is weakly expressed in all the conditions and encodes an inactive protein. Although Gas1p functions in cell wall formation, we show that it persists during sporulation but is relocalized from the plasma membrane to the epiplasm in a process requiring End3p-mediated endocytosis and the Sps1 protein kinase of the p21-activated kinase family. Some Gas1p is also newly synthesized and localized to the spore membrane, but this fraction is dispensable for spore formation. By way of contrast, the Gas2-Gas4 proteins, which are essential for spore wall assembly, are rapidly degraded after spore formation. On germination, Gas1p is actively synthesized and concentrated in the growing part of the spore, which is essential for its elongation. Thus Gas1p is the primary glucan-remodeling enzyme required in vegetative growth and during reentry into the proliferative state. The dynamic interplay among Gas proteins is crucial to couple glucan remodeling with morphogenesis in developmental transitions.
authors.affiliation: Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Rolli
authors.forename: Enrico
authors.initials: E
authors.lastname: Ragni
authors.forename: María
authors.initials: M
authors.lastname: de Medina-Redondo
authors.forename: Javier
authors.initials: J
authors.lastname: Arroyo
authors.forename: Carlos R Vázquez
authors.initials: CR
authors.lastname: de Aldana
authors.forename: Laura
authors.initials: L
authors.lastname: Popolo
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism; D002454:Cell Differentiation; D002473:Cell Wall / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004705:Endocytosis; D015966:Gene Expression Regulation, Fungal; D005936:Glucans / Q000378:metabolism*; D005964:Glucosyltransferases / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D008540:Meiosis / Q000502:physiology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013172:Spores, Fungal / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D054462:p21-Activated Kinases / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; C091908:END3 protein, S cerevisiae; C066709:GAS1 protein, S cerevisiae; D005936:Glucans; D017261:Glycosylphosphatidylinositols; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; C553583:GAS3 protein, S cerevisiae; C553582:GAS5 protein, S cerevisiae; D005964:Glucosyltransferases; D017346:Protein Serine-Threonine Kinases; C505365:Sps1 protein, S cerevisiae; D054462:p21-Activated Kinases